Claudia "Claud" Lynn Kishi is vice president of The Baby Sitter's Club, as meetings are held in her bedroom due to her personal phone line. She was born on July 11th in Stoneybrook, Connecticut at 4:36 A.M. It is not known which hospital she was born. Claudia is 13 years old and is in eighth grade at Stoneybrook Middle School and Stacey's best friend. She made her first appearance in Book #1, Kristy's Great Idea. Claudia one of the main characters in The Baby Sitters Club books by Ann M. Martin.

Claudia is the vice president of The Baby-Sitters Club, because she's the only member with a private phone line and an unlimited amount of snacks. The meetings are held in Claudia's messy bedroom in the Kishi household. Claudia provides the snacks. Since some clients forget when the meeting times are and call during times when they're not meeting, Claudia has to handle those calls. She has to write down the information, like how many kids, where the parents will be, and other important information, call all the BSC members to find out who's free to take the job, and then call the person back to tell them who the baby sitter or sitters (if there's more than four kids) will be. Claudia usually arrives to meetings on time, since they're in her own house. Claudia almost quit The Baby-Sitters Club in Book #12 Claudia and the New Girl when her new friend, Ashley Wyeth, encouraged her to drop baby sitting to make time for her art because she was very talented and shouldn't waste time on anything else. She almost quit The Baby-Sitters Club again in Book #19 Claudia and the Bad Joke when she baby sat for a practical joker who played a joke that went too far and resulted in Claudia breaking her leg. She was one of the four original members in the beginning. She is sometimes forgetful, as she sometimes took jobs for herself, without even checking if anyone else was available for the job. In fact, that led to a fight in Book #4 Mary Anne Saves the Day, between Stacey, Kristy, Mary Anne, and Claudia that lasted for months. Claudia has a special relationship with Baby-Sitters Club charge, Jamie Newton. Jamie and Lucy Newton and are two of Claudia's favourite baby sitting charges. (Jamie calls Claudia "Claudy.")

Claudia is a passionate artist and is known for her creativity and fashion sense. Claudia is addicted to junk food and Nancy Drew mysteries, and since her parents disapprove of both addictions, Claudia has to hide junk food and Nancy Drew books all over her bedroom. Claudia is cool, but she can barely spell and generally is not a strong student. She was temporarily moved down to the seventh grade. It was revealed in Book #2 Claudia and the Phantom Phone Calls that just like Janine, Claudia also has an above average IQ, which Claudia's family and teachers find surprising. If she gets all of her homework done every night (with someone in her family supervising her), she can continue to take her art classes and stay in The Baby-Sitters Club. Claudia's parents receive approximately two letters in the mail each year about how she should be working harder in school. She doesn't want to compete with Janine because she thinks she'll never live up to her. Claudia finds her schoolwork boring and can barely concentrate on it. Claudia's parents and teachers come down so hard on her because they know she can do better in school, what with her above average IQ. Janine has a genius IQ, and Claudia's parents and teachers expect her to get the same high grades, which she can't do, often telling them she's an artist, not a scholar. Claudia's parents have trouble understanding her, and understanding how Claudia and Janine can be so different, yet they are related. She is a little boy crazy and went out with Trevor Sandbourne and a couple of other boys, but none of them were very serious or lasted very long. Claudia tries to control her temper most of the time, except for one instance in Book #7 Claudia and Mean Janine where Claudia raised her hand and was about to hit Janine but refrained. She is sometimes forgetful and thinks she can be a real pain sometimes. Claudia likes the movie Star Wars, as revealed in Book #9 The Ghost at Dawn's House when the BSC members were having a sleepover, and Claudia wanted to watch Star Wars. She has a lot of her artwork on her bedroom walls and puts new things up regularly, replacing the old ones. Claudia has never been able to keep ice cream in her bedroom because it would melt. She got a hollow book to hide junk food in, during the first summer since The Baby-Sitters Club was started (during books #6 to #9). She stopped dressing up her stuffed animals in third grade and started wearing makeup in the beginning of seventh grade. Claudia is kind of a slob, and she loves to dance.

Claudia is Japanese-American with long, silky black hair and dark, almond-shaped eyes. She has been called tall and thin many times, which is amazing considering how much junk food she eats. She wears a different hair style every day and wears wild jewelry and accessories like earrings with skulls (Book #1 Kristy's Great Idea), earrings with Christmas trees that flash on and off (Book #26 Claudia and the Sad Goodbye), fedoras, and other things that most kids would never think of wearing or that their parents would even allow. She has also worn a snake bracelet (Book #7 Claudia and Mean Janine) and a ring with a fierce green dragon's head on it (Book #9 The Ghost at Dawn's House) among other things. Claudia likes bright colours, fun patterns, and funky touches to outfits, like earrings with feathers. She hates traditional clothes and never wears them. An example of a Claudia outfit is : Purple pants that stop just below her knees and held up with suspenders, white tights with clocks on them, a purple plaid shirt with a matching hat, high top sneakers, and lobster earrings. These types of clothes are Claudia's trademark. Claudia's friends have never seen her with the same hairstyle twice.

﻿Claudia is best friends with Stacey McGill, and the two generally consider themselves cooler than the rest of The Baby-Sitters Club. Stacey moved from New York and the five main babysitters in the club are featured in The Summer Before. There are stories about each of the members. It's relieved that Stacey has diabetes, and Claudia is a supporting friend of hers. They met at school sometime before Book #1 Kristy's Great Idea when Stacey dropped her notebook in the hallway, and Claudia accidentally stepped on it. They became best friends instantly. She often calls Stacey "Stace." Claudia grew up with Mary Anne Spier and Kristy Thomas because Kristy and Mary Anne lived next door to each other, and they lived across the street from Claudia on Bradford Court until Kristy moved to McLelland Road in Book #6 Kristy's Big Day, and Mary Anne moved to Burnt Hill Road in Book #31 Dawn's Wicked Stepsister. They knew each other since they were in diapers, and their families were friends. Claudia was growing up, wearing makeup, a training bra and becoming interested in boys which made Mary Anne and Kristy feel left out. Both of them noticed that Claudia was growing apart from them. Even Claudia herself realized this. Her changing interests and Mary Anne and Kristy's sadness at this realization was detailed in The Summer Before. It was even a main plot.

Claudia had a major crush on Trevor Sandbourne in Book #2 Claudia And The Phantom Phone Calls . She even daydreamed about him. Claudia has gone to dances with many boys and has talked on the telephone with some of them or eaten lunch in the school cafeteria with them, but none of her relationships lasted long or were very serious. Claudia's first major crush (and heartbreak) happened in The Summer Before.

Janine and Claudia are very different, and it's hard to believe they're sisters. While they love each other, they often argue, although they have had some nice, heartfelt moments, such as in Book #7 Claudia and Mean Janine where Janine revealed that she was jealous of Claudia because she was social and had friends, and people liked her. Claudia admitted that she was jealous of Janine because she was always receiving awards and bringing home awesome report cards and she could always make their parents proud. Claudia wishes she could make her parents proud like that. Author Ann M. Martin revealed that she based Janine and Claudia's relationship on herself and her younger sister Jane's relationship, Claudia being Jane and Janine being Ann. To see more of the relationship between Janine and Claudia, see Jaudia.

Mimi and Claudia were very close. Claudia painted several portraits of Mimi because she loved her grandmother. She felt that Mimi was the only one who understood her in her family and that she even understood her better than her friends in The Baby-Sitters Club. Claudia went to Mimi for advice and knew that Mimi would comfort her when she was upset. Claudia and Mimi shared 'special tea' together, and Mimi helped Claudia with her homework. Mimi calls Claudia "my Claudia." She is very close to Mimi throughout the series, until her death in Book #26 Claudia and the Sad Goodbye. Claudia often mentions Mimi in the books she narrates, and so do the other club members in the books they narrate. To see more of the relationship between Mimi and Claudia, see Cimi.

While Claudia isn't nearly as close to Charlotte Johanssen as Stacey is, Claudia and BSC charge Charlotte, formed a bond in Book #15 Little Miss Stoneybrook...and Dawn, when Stacey temporarily moved back to New York two books before, and Charlotte knew that Claudia and Stacey were best friends and therefore felt a connection to Claudia. She became Charlotte's new favourite baby sitter until Stacey returned in Book #28 Welcome Back Stacey. Claudia helped Charlotte prepare for the Little Miss Stoneybrook beauty pageant in Little Miss Stoneybrook...and Dawn. Since Charlotte is shy, she ended up leaving the stage in tears and went home. Later, Charlotte and Claudia went to Claudia's house to call Stacey in New York.

Stacey and Claudia have been best friends since the beginning of seventh grade when Stacey dropped her notebook in the school hallway, and Claudia accidentally stepped on it. They were instantly close friends. They both love fashion and shopping. They both are a little boy crazy, too. Claudia tries her best to understand Stacey's diabetes and only once or twice offered her candy (the first was in Book #3 The Truth About Stacey when they were all upset about The Baby-Sitters Agency and Claudia was too upset to think).